In typical PTCA procedures, a guiding catheter having a preshaped distal tip is percutaneously introduced by a Seldinger technique into the vascular system of a patient and advanced within the system until the preshaped distal tip of the guiding catheter is disposed within the ascending aorta adjacent the ostium of the desired coronary artery. The guiding catheter is relatively stiff because it has to be twisted or torqued from its proximal end, which extends outside the patient, to turn the distal tip of the guiding catheter so that it can be guided into the desired coronary ostium. A balloon dilatation catheter is introduced into and advanced through the guiding catheter and out its distal tip into the patient's coronary artery until the balloon on the distal extremity of the dilatation catheter is properly positioned across the lesion to be dilated. Once properly positioned, the balloon is inflated one or more times to a predetermined size with radiopaque liquid at relatively high pressures (e.g., generally 4-12 or more atmospheres) to dilate the stenotic region of the diseased artery. When the dilatations have been completed, the balloon is finally deflated so that the dilatation catheter can be removed from the dilated stenosis to allow the resumption of normal blood flow through the dilated artery.
There are several types of balloon dilatation catheters which are now widely available, including over-the-wire catheters, fixed-wire catheters, rapid exchange type catheters (which are a type of over-the-wire catheter) and perfusion type catheters (which may be either over-the-wire or fixed-wire catheters).
Commercially available dilatation catheters have balloons with lengths ranging from about 20 to about 40 mm to handle stenosis of various lengths. However, many times the length of the balloon chosen for an angioplasty procedure is inappropriate. For example, when multiple stenosis are to be dilated, the length of one stenosis may be of significantly different length than another requiring a balloon of different length. This necessitates using multiple catheters increasing the cost and complexity of the intravascular procedure. Additionally, dilatation catheters having a range of suitable balloon lengths must be stocked and made available to the physician. What has been needed and heretofore unavailable is a dilatation catheter with a balloon which can effectively dilate stenotic regions having a variety of lengths. The present invention satisfies this and other needs as will be described hereinafter.